<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <meta http-equiv="X-UA-Compatible" content="ie=edge">
    <title>three.js canvas -geometry - earth</title>
    <!-- 内容分发网络 从cdn引入 更快 -->
    <script src="https://cdn.bootcss.com/three.js/r83/three.min.js">
    </script>
</head>
<body>
    <canvas id="webglcanvas"></canvas>
    <script>
        var canvas,  //3d 渲染容器 webgl  
          camera, //相机功能
          scene,  //场景
        renderer; //渲染器
        var mouseX = mouseY = 0;

        var windowHalfX = window.innerWidth / 2;
        var windowHalfY = window.innerHeight / 2;
        init();
        animate();
        function init() {
            // 导演 ， 拿着相机 找到演员 摆好pose 动起来 
            // canvas 录影机  播放出来 
            canvas = document.getElementById('webglcanvas');
            camera = new THREE.PerspectiveCamera(60,
            window.innerWidth/ window.innerHeight,1,2000);
            camera.position.z = 500;
            scene = new THREE.Scene();  //场景
            scene.background = new THREE.Color(0xffffff);
            group = new THREE.Group();
            scene.add(group);
            var loader = new THREE.TextureLoader();
            loader.load('land_ocean_ice_cloud_2048.jpg', function(texture) {
                //图片已加载完
                   var geometry = new THREE.SphereGeometry(200,20,20); //形状
                   var material = new THREE.MeshBasicMaterial ({
                    map: texture    //材质
                   });
                   //建模
                   var mesh = new THREE.Mesh(geometry, material);
                   group.add(mesh);
            })
            renderer = new THREE.WebGLRenderer({
                canvas : canvas,
                antoalias: true,
            })
            renderer.setSize(window.innerWidth, window.innerHeight);
            document.addEventListener
            ('mousemove', onDocumentMouseMove,false);
          window.addEventListener('resize', onWindowResize, false);
            // renderer.render(scene, camera);
        }
        function animate() {
            requestAnimationFrame(animate);  //请求关键帧
            render();
        }
        function render () {
            camera.position.x += (mouseX - camera.position.x)*0.05;
            camera.position.y +=(-mouseY - camera.position.y)*0.05;
            camera.lookAt(scene.position);
            group.rotation.y -= 0.005;
            renderer.render(scene, camera);
        }

        function onDocumentMouseMove(event) {
    //   console.log(event.clientX,event.clientY);
    mouseX = event.clientX - windowHalfX;
    mouseY = event.clientY - windowHalfY;

        }
        function onWindowResize () {
            windowHalfX = window.innerWidth / 2;
            windowHalfY = window.innerHeight / 2;
            camera.aspect = window.innerWidth / window.innerHeight;
            renderer.setSize (window.innerWidth,window.innerHeight);

        }
    </script>


</body>
</html>